The blanket approach in Lingat Village was implemented under the Leprosy Post Exposure Prophylaxis (LPEP) programme. The aim of LPEP is to assess impact and feasibility of contact tracing and administration of single dose of rifampicin (SDR) to asymptomatic contacts of leprosy cases in the six countries (India, Nepal, Myanmar, Sri Lanka, Tanzania, Indonesia) . Indonesia however, is the only country where the blanket approach is applied. In the other countries SDR is provided to close contacts of leprosy patients only.
The objective of the blanket approach campaign was to survey the complete target population and provide all eligible individuals with SDR in one visit in a high endemic, isolated population. Because the desired coverage of more than 80% was not reached, it was decided to conduct a second visit in the next year to include those who were missed during the first visit. The inadequate coverage in the first visit was mainly due to lack of awareness in the population regarding leprosy and its consequences, although the officials and inhabitants were well informed prior to the visit (Table 2). The absentees were out to earn livelihood, because there were wage losses when staying at home in receiving the intervention. The skin examination can only be done in daylight, therefore late evening or early morning timings were not suitable, although this could increase the coverage. Certainly, the first visit increase awareness, and the second visit emphasized seriousness of the intervention, which helped to increase the coverage in the following visits. By the end of second visit, 92% were listed and 88% were screened. A third (follow-up) visit after a year was conducted to monitor the number of new cases arising in the population after the intervention during the two baseline visits. Among the people screened during the third visit, there was an apparent reduction of leprosy of around 50% among those who had previously received SDR compared to those who had not. However, a high rate of transmission is evident as 3 child cases (2–14 age group) were detected in the third visit, and 2 of them had SDR in the previous visits. Studies on effectiveness have been done before, but not always with clear conclusions, due to methodological shortcomings. In 1988, a non-controlled trial with SDR 25 mg/kg dose was implemented in the Southern Marquesas Islands [24,25,26]. The intervention achieved 98.7% coverage (2715 received SDR out of 2786 inhabitants), and additionally covered 3144 South Marquesans living elsewhere in French Polynesia. As a result, new 5 cases were detected in the next 10 years among treated population, which was significantly less than the 17 expected cases in a hypothetical situation of unchanged transmission rate. In comparison to the Polynesian population that did not receive the intervention, chemoprophylaxis was found to have an additional protective effect of 35–40%. In 1990, Pacific islands implemented chemoprophylaxis in the Federated States of Micronesia, Kiribati and the Republic of the Marshall Islands . The screening covered 70% of the population for two consecutive years, including chemoprophylaxis (both years) of rifampicin-ofloxacin-minocycline (ROM) to adults and rifampicin only to children under 15 years of age . By 1999 a substantial reduction in case detection was observed, but it could not be established that this was due to intervention .
In the year 2000, five high endemic islands in Indonesia piloted chemoprophylaxis with a defined control group  with 600 mg rifampicin for adults and 300 mg for children (6–14 years old) with approximately 3.5 months between doses. Two types of chemoprophylactic intervention strategies (blanket approach and contact tracing SDR) were compared with a control group (no chemoprophylaxis). In contact tracing SDR, prophylaxis was given to eligible contacts of all known and newly found leprosy patients only, unlike the blanket approach. The population cohort of 3965 persons was actively screened before the intervention and subsequently once a year for three years. The yearly incidence rate in the control group was 39/10,000; the cumulative incidence after three years was significantly lower in the blanket group. No difference was found between the contact tracing SDR and the control groups. This study showed that population-based prophylaxis was associated with a reduced leprosy incidence in the first three years after implementation. Subsequently the COLEP trial in Bangladesh, in which SDR was given to contacts of leprosy patients, showed an overall reduction in the incidence of leprosy in the first two years of 57% . The initial protective effect was maintained, but no difference in incidence was seen between the placebo and rifampicin groups beyond two years [22, 29, 30].
Based on the preceding studies, it can be expected that the provision of chemoprophylaxis in a blanket approach to a well-defined highly endemic population will help reduce the transmission of M. leprae in that population. Apart from overall reduction of leprosy cases in the coming years, we do expect a possible relative increase in MB cases because SDR is more effective in reducing the PB cases due to lower bacterial load than MB. The increase in MB cases can also be due to previously missed early MB cases as it is often difficult to diagnose such cases through screening. One can expect that potential MB and PB cases that are early in the incubation period may respond well to SDR, but not those MB cases which are already advanced in their clinical stage. There are however, several important remaining questions regarding implementation aspects of such approach, and on the intensity and duration of active follow-up. It cannot be expected that leprosy will disappear by itself after a one-off intervention, as the experience of the Federated States of Micronesia and the Marshall Islands sadly demonstrated. The current study in Lingat village showed that the campaign could not be completed in just one visit. In order to optimize the effect of such campaign, an effort should be made to reach as much people in a single first round or to leave limited time between the first and second round, to avoid unidentified leprosy patients continuing to spread M. leprae in their surroundings. A one-year intercept is already quite long, and it would be preferable to conduct the second round within 6 months.